Fish shell doesn't handle Windows style paths

[mati865]

Description / Steps to reproduce the issue

Unlike Bash, MSYS2's Fish shell doesn't handle Windows style paths like.

I'm not sure whether this issue belongs to the Fish upstream or here.

Noticed the problem by running COMPLETE=fish jj | source which results in broken completions. The completions are broken because that command produces:

complete --keep-order --exclusive --command jj --arguments "(COMPLETE=fish "G:\\msys64\\clang64\\bin\\jj.exe" -- (commandline --current-process --tokenize --cut-at-cursor) (commandline --current-token))"

As the workaround, I convert the path in my config:

    complete -e -c jj
    COMPLETE=fish jj | sed "s/\\\\\\\\/\//g" | source

Expected behavior

Expected Fish to behave just like Bash does:

$ "G:\\msys64\\clang64\\bin\\jj.exe" --version
jj 0.38.0-2508982cde5c7e4db0933e0b6469f9e778e71e28

$ "G:/msys64/clang64/bin/jj.exe" --version
jj 0.38.0-2508982cde5c7e4db0933e0b6469f9e778e71e28

$ "G:\\msys64\\clang64\\bin/jj.exe" --version
jj 0.38.0-2508982cde5c7e4db0933e0b6469f9e778e71e28

Actual behavior

Instead, Fish handles paths containing at least one slash well, but fails with escaped backslashes only:

❯ "G:\\msys64\\clang64\\bin\\jj.exe" --version
fish: Unknown command: 'G:\\msys64\\clang64\\bin\\jj.exe'

❯ "G:/msys64/clang64/bin/jj.exe" --version
jj 0.38.0-2508982cde5c7e4db0933e0b6469f9e778e71e28

❯ "G:\\msys64\\clang64\\bin/jj.exe" --version
jj 0.38.0-2508982cde5c7e4db0933e0b6469f9e778e71e28

Verification

• I have verified that my MSYS2 is up-to-date before submitting the report (see https://www.msys2.org/docs/updating/)

Windows Version

MINGW64_NT-10.0-26100

Are you willing to submit a PR?

No response

[kambala-decapitator]

works fine for me on fish 4.5.0:

> hexdump -C 'C:\\Users\\kamba\\.conan2\\p\\b\\libvpb713304154c88\\b\\build-release\\vpx.sln'
00000000  4d 69 63 72 6f 73 6f 66  74 20 56 69 73 75 61 6c  |Microsoft Visual|
...

EDIT: but when the command itself is a windows-style path, it doesn't indeed